This application requests funds to purchase a Leica SP5X 2-photon laser-scanning confocal microscope system for the University of Michigan campus in Ann Arbor, Michigan. Currently there is no 2-photon confocal microscope system for shared use at the University of Michigan. The system consists of a Leica SP5X inverted microscope configured to accept a Coherent ultra II Titan Sapphire IR laser for 2-photon imaging. This system is a newer form of confocal microscopy which allows real-time repeated imaging of living organism systems, cells, molecules, and ion distribution of interest while avoiding the photobleaching and phototoxicity problems associated with conventional confocal microscopes. The Leica system was selected because of its technological advancements with emission spectral selection, ease of operating software, and fast technical assistance from local service providers. The system will be housed within the Microscopy &Image Analysis Laboratory (MIL), a professionally managed University- wide imaging core, (www.milimaging.com). We anticipate that up to 70 NIH sponsored primary investigators, their co-investigators, and students as well as others in the research community on the University of Michigan campus have uses which are of technical interest to NIH advancements. Projects that will benefit from the instrumentation include mechanisms for dendritic and axonal development, secretory processes of cells, chromosomal organization, hearing loss, and tumor metastasis processes to name a few. Day-by-day maintenance, technical supervision, and instruction will be carried out by members of the MIL staff. Ongoing maintenance will be covered through a standard recharge system used in the MIL. Long-term continuity is supported by a designated reserve fund for the MIL.